The present invention relates to polyurethane type curable coating compositions. More particularly, the invention relates to a coating composition insuring a high degree of adhesion to substrates even at low temperature.
In order to improve the adhesive affinity for substrates of polyurethane type curable coating compositions, many efforts have been made to modify the starting material polyether. For example, it has been proposed to use an ethylene oxide-propylene oxide random copolymer to provide an amorphous polyether segment and thereby increase the low-temperature flexibility and, hence, adhesion of polyurethane coating films.
However, insofar as polyurethane type curable coating compositions are based on such conventional polyethers, the basically linear structure of the polyether does not insure a sufficient low-temperature flexibility of the cured coating film with consequent limited adhesion to the substrate, thus restricting the usage of the compositions.